What's the best monitor for Blender?
I would not worry about heath problems monitors might cause. They are quite safe. If you are worried about your eyesight, you should make breaks during work, let your eyes focus at things at different distances every now and then - it does not matter what monitor you have if you do not do this. I find it helpful to have a drink on my desk at work pretty much all the time - tea, juice, water, coffee - whatever you like. Fluids are good for you(well, maybe not coffee, and maybe not the ones with lots of sugar), you take your eyes off the screen every couple of minutes to take a sip and every hour or so take a walk to the toilet or to refill the drink. Works for me.

As far as color accuracy goes this gets really complicated. The prices range from something like 50&euro; to 5000&euro;. It is also possible to get devices to calibrate and profile your monitors for around 200-250&euro;, however if you are going to want to see the colors accurate in Blender, that makes absolutely no sense, since Blender does not support color management with ICC profiles that those devices produce so you can only see color tone calibration. Color profiling does not work with wide gamut or HDR displays well (see this confusing video) and color reproduction using FRC(Frame Rate Control) will most likely interfere with the process as well. So it does make sense to get a good quality display in the first place instead of trying to fix one that is not accurate to begin with and those may cost a fortune. 

You may also wish to get a 4K display since it makes a huge difference when working with Blender. You get screen space equivalent to 4 HD monitors with it and Blender has a lot of stuff that you may want to have on screen without the need for switching layouts or panel types. Being able to browse the web or/and see reference images all the time while working is also really useful so I cannot recommend 4K enough. However with that resolution if you get a screen of regular size you may not experience the benefits of it since you would need to look at it from a very close distance, so it does make sense to get a bigger screen, even as big as 43"(I honestly find it the most comfortable size for 4K). With those sizes uniformity is likely to become an issue as well(in addition to color accuracy), so you have to look out for that and if you are thinking to try a cheep one that might not be such a good idea. So it is definitely worth to consider 4K monitors for work with Blender, however that adds a lot to the price. 

As you can see there are many good reasons to spend a whole lot of money on a monitor for work with Blender and computer graphics, so I believe it will most likely come to your budget. If you can, get a huge 4K monitor recommended for work with accurate color that you can still afford. I believe one of the best options at the time I am writing is ColorEdge CG318-4K to answer your question, however I think you will want to consider some more affordable options.